This invention relates to plant cultivation, and more particularly, to a method for growing nursery stock in-field, in buried containers, and harvesting the stock from such containers, and including apparatus for practicing the method.
The growing of nursery stock such as trees, shrubs and the like in above-ground containers has been a commercial practice for many years; however, the practice is efficient and economical only during the early period of development of the plant. Nursery stock left too long in the same container not only tends to become root bound, but protracted confinement of plants in above-ground containers leads to a number of problems associated with environmental extremes, viz.: low temperatures during the winter months can damage or kill the roots of trees in above-ground containers, and the trees and containers are readily blown over by high winds, while in the summer months, high soil temperatures can retard plant and root growth. And in extremely dry weather the root system of a plant in an above-ground container can desiccate rapidly. When nursery stock si held in above-ground containers beyond the juvenile growth period, expensive materials and labor-intensive procedures are required to protect the plant and to stabilize and control its growth, e.g., by hilling the container with soil or mulch, and by staking taller plants against high winds.
In contrast, the root systems of field-grown plants are less likely to suffer from extreme weather conditions. When nursery stock is grown in the ground, the soil surrounding the plant insulates the roots from temperatures extremes while maintaining the plant in a upright positions, without staking. However, when grown in the ground without confining root growth, the plant must be timely harvested during the juvenile growing period, lest a spreading and more mature root system be damaged upon extraction of the plant from the ground, which often results in the unsatisfactory growth or even death of the nursery stock after transplanting. Root pruning or transplanting become necessary if fibrous roots are to be grown on a maturing, field-grown plant. Further, the harvesting of field-grown nursery stock is usually seasonal and dependent on weather conditions, and is into conducive of selective harvesting of the stock. Nursery stock grown in a field is conventionally harvested all at the same time. Selective harvesting of larger, field-grown stock requires that the planted rows be spaced far apart to allow passage of harvesting machinery such as digging machines and root ballers, which can be massive as the size of the plants, particularly trees, increases.
The term "ball" utilized herein, a term of the art, means the compact mass of earth or other growing medium and roots moved with a transplanted shrub or tree (Webster's New International Dictionary . . . Second Edition Unabridged.) A ball may or may not be spherical or ovoid in shape. In the "ball-and-burlap" method of transplanting, the ball is tightly wound in burlap.
The planting and growing of nursery stock in the ground, inside containers, is a method in which the walls of the container inhibit or constrict the outward growth of roots, while perforation in the container allow some roots to grow and extend into the ground outside the container. In one technique, nursery stock planted in the ground is confined within a porous fabric container prior to transplanting, and in another, in a molded, perforated plant pot having a plurality of releasable staves. Both of these methods, however, upon transplanting the nursery stock, require that the container and the plant be dug as a unit from the ground, the roots growing exteriorly of the container being broken off or removed from the ground with the container. However, removal of nursery stock in their containers from the ground incurs the same disadvantage as plants grown infield, ex container, viz:, removal by hand implement is time consuming and labor-intensive, while the use of cumbrous and expensive digging machines to extract the container and plant from the ground is capital-intensive and requires, for larger plants, the provision of fallow land between the planted rows to accommodate movement of the heavy machinery.
It is, therefor, a principal object of my invention to provide an improved method and apparatus for growing nursery stock.
A more particular object of the present invention is to provide an improved method of growing nursery stock int he ground in containers, which method combines the advantages of both container and in-field planting methods, and to provide apparatus for practice of the method.
It is another object of the present invention to provide an improved method and apparatus for growing nursery stock in-field, which obviates the loss of topsoil from the field upon harvesting the plants.
Another object of the invention is to provide an improved method, and apparatus for its practice, for growing nursery stock in-field in perennial production while maintaining closely spaced rows for most efficient use of valuable nursery acreage.
Another object of the invention is to provide an improved method and apparatus for its practice which provides partial root containment for optimum growth potential and year-round harvesting, and partial root escapement into surrounding soil for more natural root development, precluding a root-bound plant and enhancing plant stability.
Yet another object of my invention is to provide improved apparatus for growing and harvesting nursery stock in-field, in containers, and including apparatus for harvesting such nursery stock from the in-ground containers.
Another object of the invention is to provide an improved in-ground container for growing nursery stock, and a harvesting tool which coacts with the container to facilitate removal of the stock from the container while leaving the container buried in the ground.